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dc.contributor.authorRiverola Lacasta, Alberto
dc.contributor.authorMellor, A.
dc.contributor.authorAlonso Alvarez, D.
dc.contributor.authorFerre Llin, L.
dc.contributor.authorGuarracino, I.
dc.contributor.authorMarkides, C. N.
dc.contributor.authorPaul, D. J.
dc.contributor.authorChemisana Villegas, Daniel
dc.contributor.authorEkins-Daukes, N.
dc.description.abstractThe thermal emissivity of crystalline silicon photovoltaic (PV) solar cells plays a role in determining the operating temperature of a solar cell. To elucidate the physical origin of thermal emissivity, we have made an experimental measurement of the full radiative spectrum of the crystalline silicon (c-Si) solar cell, which includes both absorption in the ultraviolet to near-infrared range and emission in the mid-infrared. Using optical modelling, we have identified the origin of radiative emissivity in both encapsulated and unencapsulated solar cells. We find that both encapsulated and unencapsulated c-Si solar cells are good radiative emitters but achieve this through different effects. The emissivity of an unencapsulated c-Si solar cell is determined to be 75% in the MIR range, and is dominated by free-carrier emission in the highly doped emitter and back surface field layers; both effects are greatly augmented through the enhanced optical outcoupling arising from the front surface texture. An encapsulated glass-covered cell has an average emissivity around 90% on the MIR, and dips to 70% at 10 µm and is dominated by the emissivity of the cover glass. These findings serve to illustrate the opportunity for optimising the emissivity of c-Si based collectors, either in conventional c-Si PV modules where high emissivity and low-temperature operation is desirable, or in hybrid PV-thermal collectors where low emissivity enables a higher thermal output to be achieved.
dc.description.sponsorshipThis research was supported by the 'Ministerio de Economía y Competitividad' of Spain (grants ENE2013-48325-R, BES-2014-069596 and EEBB-I-16-11459) and the by the UK Engineering and Physical Science Research Council (EPSRC) [grant number EP/M025012/1]. A. Mellor was supported by the European Commission through Marie Sklodowska Curie International Fellowship, Grant No. DLV-657359. Re fl ection and Transmission measurements were performed by Dr. Volker Kübler in the Micro-structured Surfaces Group of Fraunhofer- ISE, Freiburg, Germany.
dc.relation.isformatofVersió postprint del document publicat a:
dc.relation.ispartofSolar Energy Materials and Solar Cells, 2017, vol. 174, p. 607-615
dc.rightscc-by-nc-nd (c) Elsevier, 2017
dc.subjectNormal cell operating temperature
dc.subjectHybrid photovoltaic-thermal
dc.titleMid-infrared emissivity of crystalline silicon solar cells

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cc-by-nc-nd (c) Elsevier, 2017
Except where otherwise noted, this item's license is described as cc-by-nc-nd (c) Elsevier, 2017